The Capcom Unity Blog announces the promised DLC for the Windows edition of Street Fighter X Tekken is now available on Games for Windows LIVE, but "an unforeseen error with the Valve submission process," is holding up its release on Steam (thanks VG247). Here's word:

To those who have been eagerly awaiting today’s DLC release for Street Fighter X Tekken on Games for Windows Live and Steam, it is our unfortunate duty to report a bit of bad news. While the GFWL DLC is in fact now live, an unforeseen error with the Valve submission process has caused a delay on Steam, preventing a timely release of the DLC on that service.

The ETA for the Steam version is now early next week. We deeply apologize for the delay, and ask for the continued patience of Steam users while we work through this error. Thank you all.